The present invention concerns the use of recording media, especially but not necessarily motion-picture film, for mixed recording of motion-picture scenes and interspersed still images.
The concept of interspersing still images with motion-picture scenes on motion-picture film has long been known. For example, in the days of silent movies, it was a common practice to project the dialogue titles as stills intermediate motion-picture scenes, to economize on the amount of film needed. More recently, a variety of audio-visual machines, especially teaching machines, have the capability of projecting film partly in a moving-image mode and partly in a still-image mode, in accordance with a preestablished program. The interruption of the projector's film transport system is controlled either by optically scanned markings on the film or by magnetic signals recorded on a control tape for the projector.
The known techniques and equipment of this type are complex and expensive, and therefore exclude the amateur or hobbyist from the possibility of saving on film by using motion-picture film for interspersed motion-picture scenes and still shots. In particular the preparation of programs using commercially available equipment exceeds the abilities of the average amateur, and is typically done by specialist firms for special applications.
With motion-picture projectors, it is a common capability to be able to interrupt film transport so that, at least for a limited period of time, a single film frame can be projected in the manner of a still shot. Also, some projectors are provided with a buffer-loop feature, so that at any desired point of the film normal-speed projection can be terminated and the projector speed then decreased or increased for special effects purposes.
A typical conventional cassette-type motion-picture film, when exposed at the normal rate of about 18 frames per second, provides a film duration of somewhat more than three minutes. Slide film of comparable purchase price affords thirty-six exposures. If one assumes that a motion-picture scene averages fifteen seconds, then a motion-picture film affords about fifteen scenes. If one assumes that a slide is projected on the average for about fifteen seconds before going on to the next slide--and in general the viewing time is longer--then it becomes apparent that the viewing time afforded by such a slide film is about three times as long as that afforded by a motion-picture film.
This ratio can be exploited with motion-picture projectors having the capability to project a single film frame as a still, or having the capability of slowing down the film-projection speed, i.e., to increase in a visually appropriate manner the amount of viewing time which the motion-picture film of given length provides. However, if the operator is to do this manually during projection of the film, he must be extremely alert and quick, a rather impractical possibility. Furthermore, in the case where, for example, a single still-shot frame intervenes between two motion-picture scenes, the operator may indeed have no way of knowing that the still-shot frame is present on the film and that he should manually stop film transport to project it as a still.
Automatic prolonging of the viewing time afforded by motion-picture projection would for the reasons explained above by very desirable, i.e., if the operator did not have to intervene in this complicated way.
Even more importantly, for ordinary amateur purposes, it would be particularly desirable to be able to record motion-picture scenes and still shots interspersed therewith on a single motion-picture film, using a single motion-picture camera and thereafter a single reproducing apparatus. In particular, if still shots are to be taken in substantial numbers, then the possibility of using the comparatively enormous length of a motion-picture film for still shots, but without limitation upon the interspersing of motion-picture scenes, would afford the average user a very great economy, and also result in space-savings when such films are stored.